抗高温高密度无土相柴油基钻井液室内研究

Research on High Temperature Resistance and High-Density Clay-Free Diesel Oil-Based Drilling Fluid

针对常规高密度油基钻井液不利于提高机械钻速且流变性难以控制的缺点，通过分子结构设计，合成了抗高温乳化剂HT-MUL和提切剂ZNTQI，并配制了抗高温高密度无土相柴油基钻井液。通过电稳定性试验和高温老化试验，评价了乳化剂、提切剂的单剂效果，并对研发的无土相油基钻井液进行了抗温性、稳定性、抗污染能力和抑制性试验。试验结果发现：HT-MUL乳化剂具有较高的破乳电压，抗温达220℃；提切剂加量为0．5％时提切效果显著；在150~220℃条件下，2．50kg／L无土相油基钻井液破乳电压在2000V左右，可抗质量分数25％蒸馏水的污染和质量分数15％CaCl2溶液的污染。研究结果表明，抗高温高密度无土相柴油基钻井液的密度可达2．50kg／L，抗温达220℃，具有良好的稳定性、悬浮性和抗污染能力，能够满足提高钻速和保护油气层的要求。

Conventional high-density oil based drilling fluids are not effective in enhancing ROP. Further, their rheological properties cannot be controlled easily. By means of creating a new molecular structural design, the high temperature resistant emulsifier, HT-MUL, and the rheology modifier, ZNTQ-I, were developed. In addition, the high temperature resistant high-density clay-free diesel oil based drilling fluid was prepared. Performances of the emulsifier and rheology modifier were individually evaluated through electric stability tests and aging tests under high temperature. The clay-free diesel oil-based drilling fluid developed was tested for its temperature resistance, stability, anti-pollution and inhibitive properties. Test results demonstrate that HT-MUL has a high emulsion-breaking voltage and temperature resistance up to 220 degrees, and a clear rheological increase is obtained for ZNTQ-I when its concentration is 0.5%. In addition, the newly-developed drilling fluid possesses an emulsion-breaking voltage of approximately 2 000 V with allowable tolerance to pollution of distilled water with mass fraction of 25 % and pollution of CaCl2 solution with mass fraction of 15% under 2. 50 kg/L and at the temperature of 150-220 degrees. Results indicate that the newly developed drilling fluid has a density up to 2.50 kg/L and tempera- ture resistance to 220 degrees. With satisfactory stability, suspension capacities and anti-pollution capabilities, the drilling fluids can help to enhance ROP and protect pay zones.